How Heavy Are Your Beliefs?



(The FreeThinking Theist)


April 18, 2017

Is your brain true or false? How much does a belief weigh? If you gain new beliefs do you gain weight? Do these questions even make sense? These are more examples of incoherent questions!

Why are these questions incoherent? Because based on the logical law of identity we know that brains and beliefs are two different kinds of things because they possess different properties. Based on the law of identity, if two things possess all the same properties then they are identical. If two things are extremely similar but one of the things has a property the other thing does not, then we know the two things are not identical.

Martians, H20, & 7-Up

Consider this thought experiment: Suppose a martian came to visit earth and had no idea what water is. He encountered two containers with similar looking liquid. One container was labeled “water,” and the other, “H20.” He conducted experiments on the two and realized that the same temperature that caused water to boil also caused H20 to boil. He also concluded that the same temperature that caused water to freeze was the same temperature that caused H20 to freeze. In fact, everything that he found to be true of water he also found true to be of H20. Thus, he was quite rational to conclude that water and H20 are the exact same thing.

He then goes and finds two plastic bottles. One labeled “Sprite” and the other labeled “7-Up.” He notes that they look identical and assumes this is probably another example of “water” and “H20.” However, he is not lazy and decides to conduct an experiment just to make sure. Upon further investigation he notes that although the two liquids are extremely similar there are a few minor differences. Sprite relies on sodium salt, 7-Up makes use of potassium salt. Thus, he concludes that Sprite and 7-Up do not share all the same properties and therefore, these liquids, although quite similar, are not identical.

Brains & Beliefs

Many people today think that a human is nothing more than a body and brain. They think that all beliefs can be relegated to states of the brain. But upon closer investigation we should note that brain states and beliefs possess different properties. As my good friend Eric Hernandez says:

“Beliefs have the property of being true or false, but states of the brain do not possess a property of being true or false.”

Moreover, brains actually weigh something (the average weight of an adult brain is 46.4 oz/2.9 lbs). However, beliefs do not possess a weight. Indeed, the high school wrestler trying to cut weight for the dual cannot accomplish his goal by simply getting amnesia. An atheist with a “lack of belief” that God exists, does not always weigh less than the Christian who holds the belief that God does exist. This is because beliefs do not have the kind of property that can be measured on a scale — beliefs are measured regarding truth-value.

It logically follows that the two things (brain states and beleifs) cannot be the same thing. This is based on the law of identity. Thus, if one is to disagree, it is to affirm their own illogicality.

Substance Dualism 

With the logical law of identity in mind we can reach some powerful deductive conclusions. First, consider the fact that you and I are (at the least) possibly “disembrainable” (after all, near-death experiences could possibly be true), but my brain is not possibly disembrainable. This shows that I am not my brain because there is something true of me which is not true of my brain. Namely, I am the sort of thing that could survive death (even if I do not), but the brain cannot logically survive its destruction. J.P. Moreland provides a deductive syllogism making the case:  

  1. The law of identity is true: If x is identical to y, then whatever is true of x is true of y and vice versa.
  2. I can strongly conceive of myself as existing disembodied.
  3. If I can strongly conceive of some state of affairs S that S possibly obtains, then I have good grounds for believing that S is possible.
  4. Therefore, I have good grounds for believing of myself that it is possible for me to exist and be disembodied.
  5. If some entity x is such that it is possible for x to exist without y, then (i) x is not identical to y, and (ii) y is not essential to x.
  6. My body (or brain) is not such that it is possible to exist disembodied, i.e., my body (or brain) is essentially physical.
  7. Therefore, I have good grounds for believing of myself that I am not identical to my body (or brain) and that my physical body is not essential to me.

This argument provides grounds for one to rationally affirm that substance dualism is (at the least) plausibly true. With the same law of identity in mind, Jacobus Erasmus and I have crafted the Brains & Beliefs Argument that provides reason to doubt naturalism:

1- If naturalism is true, then a belief is identical to some physical brain state.
2- If a belief is identical to some physical brain state, then the belief and the brain state have the exact same set of properties.
3- Therefore, if naturalism is true, then a belief has the exact same set of properties as some physical brain state.
4- A belief does not have the exact same set of properties as some physical brain state (since a belief has the property of being either true or false, and a physical brain state lacks this property).
5- Therefore, naturalism is false.

This argument appeals to the logical law of identity to show that if beliefs and brain states possess different properties, then naturalism is false. Since beliefs and brain states possess different properties, we have an argument against naturalism. Add this to the list of the ever-increasing cumulative case of arguments that “tip the scales” of reason against naturalism (here is the tip of the iceberg):

The Kalam Cosmological Argument
The Leibnizian Cosmological Argument
The Moral Argument
The Teleological Argument
The Ontological Argument
The Evolutionary Argument Against Naturalism
The Freethinking Argument Against Naturalism
The Historical Argument for the Resurrection of Jesus

And remember…

Stay reasonable (Philippians 4:5),

Tim Stratton


For my friends who are logic junkies, check out the symbolic form of my argument offered by Jacobus Erasmus:

Let “N” mean “naturalism is true”, let “Bx” mean “x is a human belief”, let “Sx” mean “x is a physical brain state”, let “I(x,y)” mean “x is identical to y”, and let “P(x,y)” mean “y has the property x”. Then:

1. N →  ∀x{Bx →  ∃y[Sy ∧ I(x,y)]}           Premise

2. ∀x{Bx →  ∃y[Sy ∧ I(x,y)]} →  ∀x{Bx →  ∃y[Sy ∧ ∀z{P(z,x) → P(z,y)]}       Premise

3. N →  ∀x{Bx →  ∃y[Sy ∧ ∀z{P(z,x) → P(z,y)]}           1, 2, Hypothetical Syllogism

4. ¬∀x{Bx →  ∃y[Sy ∧ ∀z{P(z,x) → P(z,y)]}           Premise

5. ¬N               3, 4, Modus Tollens

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About the Author



(The FreeThinking Theist)

Timothy A. Stratton (PhD, North-West University) is a professor at Trinity College of the Bible and Theological Seminary. As a former youth pastor, he is now devoted to answering deep theological and philosophical questions he first encountered from inquisitive teens in his church youth group. Stratton is founder and president of FreeThinking Ministries, a web-based apologetics ministry. Stratton speaks on church and college campuses around the country and offers regular videos on FreeThinking Ministries’ YouTube channel.

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